Oracle® Solaris 11.2 Tunable Parameters Reference Manual

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Updated: December 2014



Controls the maximum size of the data portion of an NFS version 3 READ, WRITE, READDIR, or READDIRPLUS request. This parameter controls both the maximum size of the request that the server returns as well as the maximum size of the request that the client generates.

Data Type

Integer (32-bit)


1,048,576 (1 MB)


0 to 231 - 1




Yes, but this parameter is set per file system at mount time. To affect a particular file system, unmount and mount the file system after changing this parameter.


None. However, setting the maximum transfer size on the server to 0 is likely to cause clients to malfunction or just decide not to attempt to talk to the server.

There is also a limit on the maximum transfer size when using NFS over the UDP transport. UDP has a hard limit of 64 KB per datagram. This 64 KB must include the RPC header as well as other NFS information, in addition to the data portion of the request. Setting the limit too high might result in errors from UDP and communication problems between the client and the server.

When to Change

To tune the size of data transmitted over the network. In general, the nfs:nfs3_bsize parameter should also be updated to reflect changes in this parameter.

For example, when you attempt to increase the transfer size beyond 32 KB, update nfs:nfs3_bsize to reflect the increased value. Otherwise, no change in the over-the-wire request size is observed. For more information, see nfs:nfs3_bsize.

If you want to use a smaller transfer size than the default transfer size, use the mount command's –wsize or –rsize option on a per-file system basis.

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